Arthroscopic Surgical Temperature Control System

ABSTRACT

An arthroscopic surgical temperature control system and method able to monitor and control the temperature within a surgical site during arthroscopic ablation procedures in order to prevent tissue damage is provided.

This application is a continuation of U.S. application Ser. No.16/660,637 filed Oct. 22, 2019, which is a continuation of U.S.application Ser. No. 14/508,818, filed Oct. 7, 2014, now U.S. Pat. No.10,448,993, which is a continuation of U.S. application Ser. No.11/228,046, filed Sep. 15, 2005, now U.S. Pat. No. 8,852,184.

FIELD OF THE INVENTIONS

The inventions described below relate the field of arthroscopic surgicalequipment and more specifically, to radio frequency ablation systems.

BACKGROUND OF THE INVENTIONS

During minimally invasive surgeries, surgical instruments such asablation probes, trocars, cannulas, and optical medical devices,including endoscopes, cystoscopes, arthroscopes, laparoscopes, etc., areinserted through small incisions or portals in a patient's body or bodycavity and manipulated to perform surgical procedures within thepatient.

Minimally invasive surgical procedures are safer than open surgery andresult in quicker patient recovery, shorter hospital stays, and lowerhealth care costs. Accordingly, minimizing invasiveness continues to beof importance, and there is a continuing need for devices and methodsthat achieve this objective.

One area that has benefited from minimally invasive surgical techniquesis arthroscopic surgery. Arthroscopic surgery such as shoulder surgeryhas evolved over the last several years from being an open surgicalprocedure to an arthroscopic surgical procedure. This evolution is theresult of technological advances in equipment, instruments and implants.

Radio frequency ablation devices are often used during arthroscopicsurgical procedures such as arthroscopic shoulder surgery. Radiofrequency ablation is used, among other applications, to smooth thesurface as well as to seal fissures in the cartilage found in joints,articular cartilage. The goal of such treatment is to provide mechanicalstability while preventing the expansion of degenerative lesions withinthe cartilage matrix. Use of thermal energy on articular cartilage isnot without risk. Exposure of mature cartilage cells, chondrocytes, touncontrolled heat can cause cell death and alter the mechanicalproperties of its surrounding matrix.

Joints, such as shoulders and knees, have joint space with small amountsof fluid volume available within the surgical site. When radio frequencyablation probes are used in joints with small joint space, thesurrounding fluid in the joint can quickly heat up as the fluid acts asa heat sink. Temperatures exceeding 113° C. in surrounding non-targetedtissue can have adverse effects on the surgical site, surrounding tissueand the patient. Temperatures above 113° F. can cause cartilage tissuedeath rapidly. Presently, fluid temperatures within arthroscopicsurgical sites are not specifically monitored during surgery and stepsare not taken to maintain the fluid temperatures at safe levels, such aslevels between 97° F. and 108° F., within the surgical site duringablation. Systems and methods are needed to monitor and control thetemperature within a surgical site during arthroscopic surgicalprocedures in order to prevent tissue damage.

SUMMARY

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a method of performing arthroscopic surgery on apatient using the temperature control system.

FIG. 2 illustrates the inflow/outflow sheath of the temperature controlwith an arthroscopic instrument disposed within the sheath.

FIG. 3 illustrates a cross-sectional view of the inflow/outflow sheathin the temperature control system.

FIG. 4 illustrates a cross-sectional view of the inflow/outflow sheathin the temperature control system.

FIG. 5 illustrates a cross-sectional view of the inflow/outflow sheathin the temperature control system.

FIG. 6 illustrates a cross-sectional view of the inflow/outflow sheathin the temperature control system.

FIG. 7 illustrates a cross-sectional view of the inflow/outflow sheathin the temperature control system.

FIG. 8 illustrates a cross-sectional view of the inflow/outflow sheathin the temperature control system.

FIG. 9 illustrates the chilling module in detail.

FIG. 10A illustrates a chilling module comprising a canister ofrefrigerant.

FIG. 10B illustrates a chilling module comprising a canister ofrefrigerant.

FIG. 11 shows a temperature control system with a mixing valve.

FIG. 12 illustrates the temperature control system having an in-linetemperature-warning device.

FIG. 13A depicts a temperature-warning device.

FIG. 13B depicts a temperature-warning device.

DETAILED DESCRIPTION OF THE INVENTIONS

FIG. 1 illustrates a method of performing arthroscopic surgery on apatient's shoulder 1 using the temperature control system 2. Thetemperature control system 2 is shown inserted into a joint capsule 3 ofa shoulder of a patient. Various anatomical landmarks are depictedincluding the patient's clavicle 4, scapula 5 and humerus 6. Anarthroscopic instrument such as an arthroscope 7 is disposed within thetemperature control system. The temperature control system 2 comprises atemperature sensor 8 operably coupled to an inflow/outflow sheath 9, afluid source 10, a chilling module 11 in fluid communication with thefluid source and the inflow/outflow sheath 9 and a control system 12 inelectrical communication with the temperature senor 8 and the chillingmodule 11.

During arthroscopic shoulder surgery, the surgeon introduces thearthroscope into the shoulder via a first portal in order to visualizethe surgical field. An ablation device is introduced through a secondportal to smooth surfaces and seal fissures in articular cartilage.Optionally, an irrigating instrument may be introduced through a thirdportal in order to distend the joint, irrigate the surgical field andthereby maintain a clear view. As discussed below, a temperature controlsystem may used to control fluid temperature in the surgical site of theshoulder.

FIG. 2 illustrates the inflow/outflow sheath of the temperature controlhaving an arthroscopic instrument such as an arthroscope disposed withinthe sheath. Arthroscopic instruments can also include energy deliverydevices such as ablation devices, arthroscopes, endoscopes, awls, picks,shavers, etc. The inflow/outflow sheath is a tube of resilient material,such as a sterilizable polymer like soft plastic or rubber,characterized by a central lumen. The inner diameter of the atraumaticsheath is sized and dimensioned to closely fit over the outer diameterof an arthroscopic instrument. The tube is characterized by a distalsection 13 having a distal tip 14 and a proximal section 15. The distaltip 14 of the sheath 9 is provided with a beveled or rounded shape andan opening that is slightly smaller in diameter than the outer diameterof the distal tip of the arthroscope. The distal section of the sheathfurther comprises holes or other fluid apertures 16 placed in fluidcommunication with a fluid source or vacuum source. The proximal section15 of the atraumatic sheath is provided with a hub 17 manufactured froman elastomer to allow medical personnel to easily pull the atraumaticsheath over and secure the sheath to the ablation device, rigid cannula,and/or arthroscopic instrument. The hub 17 is adapted for coupling to afluid source and/or a vacuum source.

Holes 16 are provided in the outer wall of the distal section 13 of thesheath. The holes communicate with one or more inflow or outflow lumensin the sheath. The lumen or lumens communicate with a vacuum source,fluid source, therapeutic agent source or a combination of sources.Thus, the holes provide for the inflow and outflow of fluids to asurgical site during a procedure.

When the temperature control system 2 is in use, a user inserts thearthroscope or other arthroscopic intrument into the sheath. The distaltip expands as the distal end of the arthroscope slides past the distaltip of the sheath. Because the inner diameter of the tip is less thanthe outer diameter of the ablation device, the tip will form a sealfluid resistant seal with the outer surface of the ablation device.

A temperature sensor 8, such as a thermocouple, is disposed on thedistal section 13 of the sheath 9. During surgery, the temperaturesensor is placed in thermal communication with the fluid within thesurgical site. Other devices for measuring temperature may be used as atemperature sensor 8 including thermistors, fiberoptics or other devicescapable of measuring temperature. Alternatively, the temperature of thesurgical site can be determined by measuring the temperature of theoutflow fluid from the surgical site. The fluid being evacuated from asurgical site through the arthroscopic sheath (the outflow fluid) may bemonitored using a temperature sensor placed in fluid communication withthe outflow fluid to determine the temperature within the surgical site.

FIGS. 3 through 8 illustrate cross-sectional views of variousconfigurations of the inflow/outflow sheath 9 in the temperature controlsystem. FIG. 3 shows a cross-sectional view of the inflow/outflow sheathusing the inner surface 18 of the outer wall 19 of the tube with theouter surface 20 of the ablation instrument to form inflow and outflowouter lumens 21, 22, 23 and 24. An inflow lumen allows fluid from afluid source to flow into a surgical site while an out flow lumen allowsfluid to be evacuated from a surgical site. Relatively stiff ribs 25extending radially from the inner surface of the outer wall and runninglongitudinally along the sheath form a seal with the outer surface ofthe ablation device, thereby creating the four outer lumens. The ends ofthe ribs may be provided with elastic flanges 26 or extensions toenhance the seal made between the ribs and the ablation device. Thisconfiguration reduces the overall size of the combined inflow/outflowsheath and ablation device.

As depicted in FIG. 3, the arthroscope 7 is inserted into the sheath 9through the central lumen 27. The ablation device 7 may or may not becovered by a secondary protective sheath prior to insertion. Onceinserted, the outer surface of the ablation device 7 comes in contactwith the flanges or extensions of the ribs. A raised distinct tract,also referred to as a land, may be used to contact the outer surface ofthe ablation device when the ribs do not have flanges or extensions. Theforce of the outer surface of the ablation device pushing against theribs 25 and the rib flanges or rib extensions forms a seal between theribs and the outer surface of the ablation device 7. Outer lumens 21,22, 23 and 24 are created by the ribs 25, the outer surface of theablation device 20, and inner surface 18 of the outer wall of theinflow/outflow sheath 9. The ribs 25 act as longitudinal struts thatprevent the sheath 9 from collapsing as they support the sheath undercompression. The ribs 25 reduce the unsupported span of the thin outerwall 19 in the traverse axis, further preventing the collapse of thesheath. The seals formed by the contact between the ribs and the outersurface of the ablation device prevent fluids from flowing between theouter lumens. The outer lumens 21, 22, 23 and 24 facilitate thesubstantially continuous inflow and outflow of fluids to and from asurgical site through the holes in the sheath. Check valves or gates mayalso be coupled to the inner surface of the inflow/outflow sheath withinthe outer lumens to prevent outflow fluids from flowing back towards thesurgical site and to prevent inflow fluids from flowing out the proximalend of the sheath. Fluid can be introduced to the surgical site throughthe inflow/outflow sheath using an arthroscopy pump or by gravity feed.Furthermore, fluid is evacuated from a surgical site through theinflow/outflow sheath using a vacuum source, siphon or gravity.

The chilling module 11 is illustrated in detail in FIG. 9. The chillingmodule is a device capable of lowering the temperature of fluid prior toentering the surgical site. During surgical procedures requiringablation, inflow fluid is cooled prior to entering the surgical site.The chilling module comprises one or more heat sinks 35, athermoelectric or Peltier cooler 36 having a fan, and a control system12.

As shown in FIG. 9, a fluid inflow 37 tube in fluid communication withthe inflow/outflow sheath and a fluid source 10 is interwoven betweenone or more heat sinks 35. The Peltier cooler 36 is placed in thermalcommunication with the heat sinks 35. The control system 12 is inelectrical communication with the Peltier module 36 and the temperaturesensor 8 is disposed on the distal section of the sheath. Using thethermocouple, the control system 12 monitors the temperature of thesurgical site. When the temperature exceeds safe levels, such asexceeding 113° C., the control system instructs the Peltier moduleautomatically, without user intervention, to cool the inflow fluid. Theinflow fluid is cooled to a temperature sufficient to reduce thetemperature within the surgical site to a safe level in order to preventtissue damage. When the temperature in the surgical site reaches a safelevel (a temperature level that does not have the potential to causedamage to surrounding tissue) the control system instructs the coolingmodule automatically to reduce or cease lowering the temperature of theinflow fluid. A user can also use the control system directly to controlthe temperature level of the inflow fluid with a user interface operablycoupled to the control system. A temperature sensor reader and displaycan also be placed in electrical communication with the temperaturesensor and the control system. The reader is provided with an LCD and iscapable of displaying the temperature taken by the temperature sensor,warnings, graphical depictions and data.

The chilling module 11 can comprise other devices suitable formanipulating the temperature of inflow fluid prior to entering thesurgical site including heat sinks, refrigerators, heat exchangers,chemical and non-chemical ice packs, and refrigerants. The chillingmodule 11 may be a separate device in-line with an arthroscopic pump orbuilt into an arthroscopic pump operating in line with a fluid deliverysystem. FIGS. 10A and 10B illustrate a chilling module 11 comprising acanister of refrigerant. Here, the chilling module 11 comprises acanister 38 having an input aperture 39 and a removable lid 40. Thecanister is filled with ice, refrigerated gel or other refrigerantthrough the input aperture. The inflow tube 37 is disposed about theexterior of the canister and removably coupled to the canister using aretention tab 41. The inflow tube is placed in thermal communicationwith the canister. When inflow fluid from a fluid source passes throughthe inflow tube as illustrated in FIG. 10B, the temperature of theinflow fluid is reduced prior to entering a surgical site by therefrigerant within the canister.

FIG. 11 shows an alternative configuration of the temperature controlsystem 2 and method of cooling or heating the inflow fluid. Here, amixing valve 42 is placed in fluid communication with a first fluidsource 43 having warm irrigation fluid, a second fluid source 44 havingcool irrigation fluid and the inflow/outflow sheath 9. The controlsystem 12 is placed in electrical communication with the temperaturesensor 8 disposed on the sheath and the mixing valve 42. During surgicalprocedures, the temperature sensor 8 takes temperature measurements fromthe surgical site. The control system 12 instructs the valve 42 to mixfluid from the first fluid source 43 and the second fluid source 44 toobtain an appropriate temperature for the inflow fluid to maintain thesurgical site temperature at a safe level.

As shown in FIG. 12, in-line temperature-warning devices 48 may beincorporate in the temperature control system 2. Fluid is evacuated fromthe surgical site through the inflow/outflow sheath 9 to a vacuum source49 with a fluid outflow tube 50. Temperature-warning devices havingin-line temperature sensors may be placed in thermal communication withthe outflow fluid. This is accomplished by placing the sensors in fluidcommunication with the outflow fluid or by placing the sensors incontact with the outflow tube. The sensors are operably coupled towarning devices that provide visual, audible or visual and audiblewarnings when temperatures exceed a safe threshold. Thetemperature-warning devices can be provided as an integral part of theoutflow tube or as temperature warning collars that provide visual,audible or visual and audible warnings when temperatures exceed a safethreshold.

FIG. 13A depicts a temperature-warning device. The temperature-warningdevice comprises a collar 51 of polymeric material having an innerdiameter sized and dimensioned to slip fit over a fluid outflow tubefrom a surgical site. The collar 51 may also be provided with fittings52 capable of operably coupling the collar to the outflow tube and fluidsource. The temperature-warning device further comprises a temperaturesensor 53 such as a thermocouple that can be placed in thermalcommunication with outflow fluid through contact with the wall of theoutflow tube or by being placed in fluid communication with the outflowfluid. The temperature-warning device provides audible warnings ofdangerous temperature within a surgical site to users by placing thethermocouple in electrical communication with a control integratedcircuit board 54, a piezoelectric buzzer 55 and a power source 56disposed within the collar. A digital display 57 may also be providedcapable of displaying the temperature and visual warnings. The controlboard is able to monitor the temperature of the outflow fluid using thethermocouple and activate the piezoelectric buzzer when the temperatureof the outflow fluid exceeds a safe threshold.

In an alternative configuration of the temperature-warning device shownin FIG. 13B, a collar 51 of polymeric material having an inner diametersized and dimensions to slip fit over a fluid outflow tube is providedwith a visual temperature indicator 62 such as a thermochromic liquidcrystal thermometer. Thermochromic Liquid Crystals (TLC's) are highlysensitive materials that respond to temperature. Liquid crystals canchange from black to a rainbow of colors upon heating and then back toblack again upon cooling. Furthermore, liquid crystals can be formulatedinto thermometers with a wide or a narrow temperature sensitivity andcan be made into any size or shape. The thermometer disposed within thecollar can be placed in thermal communication with the outflow fluid byfluid communication with the outflow fluid flowing through the collar.Alternatively, the thermometer can be placed in thermal communicationwith the outflow fluid through the wall of the outflow tube disposedwithin the collar. The thermochromic liquid crystal thermometer in thecollar provides a visual indicator to a user by changing colors when thetemperature of the outflow fluid exceeds a threshold that indicates thefluid temperature within the joint is approaching 113° F.

When in use during arthroscopic shoulder surgery, an arthroscope deviceis inserted through the central lumen of the sheath in the temperaturecontrol device. The arthroscope with the sheath is then introducedthrough a first portal to visualize the surgical site. The surgeonintroduces the ablation device into the shoulder via a second portal.The ablation device is used to smooth surfaces and seal fissures inarticular cartilage. The sheath provides fluid inflow and outflow to thesurgical site. The surgeon will activate the radio frequency ablationdevice during surgery generating heat within the surgical site. Thetemperature sensor disposed on the distal end of the sheath senses thetemperature of the fluid within the surgical site. When the temperatureexceeds a safe threshold, such as a temperature exceeding 108° F., thecontrol system in electrical communication with the temperature sensorand the chilling module instructs the chilling module to cool down theinflow fluid. The lower temperature inflow fluid is introduced to thesurgical site and reduces the temperature at the surgical site to a safelevel (below 113° F.) that does not cause damage to surrounding tissue.Once acceptable temperature levels have been reached, the chillingmodule can be used to maintain the temperature level at the surgicalsite by cooling the inflow fluid when necessary. During arthroscopicsurgery, it is important for surgeons to complete the surgery in atimely manner to avoid fluid extravasation, reduce the chance ofinfection, minimize complications and reduce medical costs.

While the preferred embodiments of the devices and methods have beendescribed in reference to the environment in which they were developed,they are merely illustrative of the principles of the inventions. Otherembodiments and configurations may be devised without departing from thespirit of the inventions and the scope of the appended claims.

I claim:
 1. A system for use in arthroscopic surgery comprising: asheath characterized by a central lumen, a distal section and a proximalwherein the central lumen is sized and dimensioned to receive anarthroscopic instrument, said sheath further comprising an inflow lumenand an outflow lumen; a temperature sensor disposed on distal section ofthe sheath; a mixing valve in fluid communication with the inflow lumen;a first fluid source containing warm irrigation fluid and in fluidcommunication with the mixing valve; a second fluid sources containingcool irrigation fluid and in communication with the mixing valve; and acontrol system in electrical communication with the temperature sensorand the mixing valve, said control system capable of operating themixing valve to mix fluid from the first fluid source and the secondfluid source to lower the temperature of an inflow fluid from the fluidsource when a temperature from a surgical site measured by thetemperature sensor exceeds a safe threshold temperature.
 2. The systemof claim 1 further comprising a fluid aperture disposed on the distalsection of the sheath in fluid communication with the inflow lumen. 3.The system of claim 1 further comprising a fluid aperture in fluidcommunication with the outflow lumen.
 4. The system of claim 1 furthercomprising a temperature-warning device in thermal communication with anoutflow fluid from the outflow lumen.
 5. The system of claim 4 whereinthe temperature-warning device provides an audible warning whentemperature of the outflow fluid exceeds a safe threshold.
 6. The systemof claim 4 wherein the temperature-warning device provides a visualwarning when temperature of an outflow fluid exceeds a safe threshold.7. A method for performing arthroscopic surgery comprising: providing asheath characterized by a central lumen, a distal section and a proximalwherein the central lumen is sized and dimensioned to receive anarthroscopic instrument, said sheath further comprising an inflow lumenand an outflow lumen, one or more fluid apertures disposed on the distalsection in fluid communication with the inflow lumen and the outflowlumen and a temperature sensor disposed on distal section; providing anablation device; performing an arthroscopic surgical procedure at asurgical site using the ablation device; taking fluid temperaturemeasurements within the surgical site with the temperature sensor;cooling an inflow fluid prior to entering the surgical site with amixing valve that mixes fluid received from a first fluid source and asecond fluid source in order to keep temperatures at the surgical sitebelow a threshold based on the temperature measurements taken by thetemperature sensor.